Crosslinking materials from biorenewable aconitic acid

ABSTRACT

A process includes forming a bio-derived crosslinking material from biorenewable aconitic acid. The process includes initiating a chemical reaction to form a bio-derived crosslinking material that includes multiple functional groups. The chemical reaction includes converting each carboxylic acid group of a biorenewable aconitic acid molecule to one of the multiple functional groups.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priority from U.S. patent application Ser. No. 15/470,279, filed on Mar. 27, 2017.

BACKGROUND

Polydimethylsiloxane (PDMS) is among the most widely used silicon-based polymers, and the most widely used organic silicon-based polymer. PDMS materials have a wide range of applications including contact lenses, medical devices, soft lithography processes, shampoos, caulking, and lubricants (among other alternatives). One reason for the wide-ranging applications for PDMS materials is the variety of ways in which the properties of PDMS may be controlled through polymer crosslinking. By employing PDMS and small organic molecules with different organic functional groups, many possibilities exist for different PDMS materials to be crosslinked in different ways.

SUMMARY

According to an embodiment, a process of forming a bio-derived crosslinking material from biorenewable aconitic acid is disclosed. The process includes initiating a chemical reaction to form a bio-derived crosslinking material that includes multiple functional groups. The chemical reaction includes converting each carboxylic acid group of a biorenewable aconitic acid molecule to one of the multiple functional groups.

According to another embodiment, a process of forming a crosslinked polymeric material is disclosed. The process includes utilizing a material derived from a biorenewable aconitic acid molecule as a bio-derived crosslinking material to form the crosslinked polymeric material.

According to another embodiment, a crosslinked polydimethylsiloxane (PDMS) material is disclosed. The crosslinked PDMS material is formed by a process that comprises chemically reacting a functionalized PDMS material with a bio-derived crosslinking material that is derived from a biorenewable aconitic acid molecule.

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple vinyl groups that is formed from a biorenewable cis-aconitic acid molecule, according to one embodiment.

FIG. 1B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple vinyl groups that is formed from a biorenewable trans-aconitic acid molecule, according to one embodiment.

FIG. 2A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple acetate groups that is formed from a biorenewable cis-aconitic acid molecule, according to one embodiment.

FIG. 2B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple acetate groups that is formed from a biorenewable trans-aconitic acid molecule, according to one embodiment.

FIG. 3A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from a biorenewable cis-aconitic acid molecule, according to one embodiment.

FIG. 3B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from a biorenewable trans-aconitic acid molecule, according to one embodiment.

FIG. 4A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from a biorenewable cis-aconitic acid molecule, according to one embodiment.

FIG. 4B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from a biorenewable trans-aconitic acid molecule, according to one embodiment.

FIG. 5A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple hydroxyl groups that is formed via reduction of a biorenewable cis-aconitic acid molecule, according to one embodiment.

FIG. 5B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple hydroxyl groups that is formed via reduction of a biorenewable trans-aconitic acid molecule, according to one embodiment.

FIG. 6A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple vinyl groups that is formed from the bio-derived crosslinking material of FIG. 5A, according to one embodiment.

FIG. 6B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple vinyl groups that is formed from the bio-derived crosslinking material of FIG. 5B, according to one embodiment.

FIG. 7A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple vinyl groups that is formed from the bio-derived crosslinking material of FIG. 5A, according to one embodiment.

FIG. 7B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple vinyl groups that is formed from the bio-derived crosslinking material of FIG. 5B, according to one embodiment.

FIG. 8A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple acetate groups that is formed from the bio-derived crosslinking material of FIG. 5A, according to one embodiment.

FIG. 8B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple acetate groups that is formed from the bio-derived crosslinking material of FIG. 5B, according to one embodiment.

FIG. 9A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from the bio-derived crosslinking material of FIG. 5A, according to one embodiment.

FIG. 9B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from the bio-derived crosslinking material of FIG. 5B, according to one embodiment.

FIG. 10A is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from the bio-derived crosslinking material of FIG. 5A, according to one embodiment.

FIG. 10B is a chemical reaction diagram illustrating a process of forming a crosslinked PDMS material using a bio-derived crosslinking material having multiple thiol groups that is formed from the bio-derived crosslinking material of FIG. 5B, according to one embodiment.

DETAILED DESCRIPTION

The present disclosure describes crosslinkers derived from the biorenewable molecule aconitic acid (cis-aconitic acid and/or trans-aconitic acid) and methods of forming bio-derived crosslinkers from the biorenewable molecule aconitic acid. The biorenewable molecule aconitic acid is an organic acid that may be derived from sugarcane or citric acid. The multiple carboxyl groups make the biorenewable molecule aconitic acid a suitable cross-linking agent. In the present disclosure, prior to cross-linking, aconitic acid may be reacted with other bio-derived organic molecules, reduced, or reduced and then reacted with other bio-derived organic molecules to synthesize different cross-linkable molecules with a variety of functional groups (e.g., for binding into a variety of polymer systems). Utilizing derivatives of biorenewable aconitic acid as crosslinking materials may increase the biorenewable content of a crosslinked polymeric material, such as a crosslinked polydimethylsiloxane (PDMS) material, for use in various applications.

The bio-derived crosslinking materials of the present disclosure may be applied to PDMS (or other polymers) for different applications. Examples of alternative polymers include polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyurethane (PU), or acrylics, among other alternatives. In some cases, curing may be performed during processing of a desired material, resulting in a completely crosslinked polymer. In other cases, the crosslinkers may be mixed with PDMS but left in a partial or un-crosslinked state that can be left to crosslink upon addition to the PDMS for a particular desired application (e.g., for a caulking or coating application, among other alternatives).

FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, and 4B illustrate examples of cross-linkable molecules that may be formed from the biorenewable molecule aconitic acid. FIGS. 1A, 2A, 3A, and 4A illustrate that the cis-aconitic acid isomer may be modified with one of a variety of functional groups that are used to cross-link or cure polymers, such as PDMS (among other alternatives). FIGS. 1B, 2B, 3B, and 4B illustrate that the trans-aconitic acid isomer may modified with one of a variety of functional groups that are used to cross-link or cure polymers, such as PDMS (among other alternatives).

FIGS. 5A and 5B illustrate that the biorenewable molecule aconitic acid may be reduced to a tri-alcohol and used on its own as a cross-linker, with FIG. 5A illustrating the reduction of the cis-aconitic acid isomer and FIG. 5B illustrating the reduction of the trans-aconitic acid isomer.

FIGS. 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10A, and 10B illustrate examples of cross-linkable molecules that may be formed from the reduced aconitic acid molecules depicted in FIGS. 5A and 5B. FIGS. 6A, 7A, 8A, 9A, and 10A illustrate that the reduced aconitic acid molecule formed from the cis-aconitic acid isomer (as depicted in FIG. 5A) may modified with one of a variety of functional groups that are used to cross-link or cure polymers, such as PDMS (among other alternatives). FIGS. 6B, 7B, 8B, 9B, and 10B illustrate that the reduced aconitic acid molecule formed from the trans-aconitic acid isomer (as depicted in FIG. 5B) may modified with one of a variety of functional groups that are used to cross-link or cure polymers, such as PDMS (among other alternatives).

Referring to FIG. 1A, a chemical reaction diagram 100 illustrates a particular embodiment of a process of utilizing the biorenewable cis-aconitic acid isomer to form a first bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(1)” in FIG. 1A) that includes multiple vinyl groups. FIG. 1A further illustrates that the first bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 1A illustrates that the cis-aconitic acid molecule may be reacted with allyl bromide via a substitution reaction to form a crosslinker with multiple vinyl groups. In some cases, the allyl bromide may be synthesized in one step from biorenewable allyl alcohol.

As a prophetic example, cis-aconitic acid may be added to a suspension or solution of a base (e.g., potassium carbonate) in an organic solvent, such as ethanol, at 0° C. The reaction mixture may be stirred for 10 minutes before adding allyl bromide (4 equiv.), dropwise. The reaction mixture may be stirred for approximately 7 days and then deionized water is added to generate an aqueous phase. The aqueous and organic layers may then be separated. The aqueous layer may be extracted with a suitable solvent and rinsed with brine. The organic layer may be dried over magnesium sulfate (MgSO₄) and the solvent may be removed in vacuo. The residue is purified by distillation or column chromatography.

The second chemical reaction depicted at the bottom of FIG. 1A illustrates that the bio-derived crosslinking material having multiple vinyl groups may be utilized to form a crosslinked polymeric material (identified as “Crosslinked PDMS Material(1)” in FIG. 1A). FIG. 1A illustrates a particular embodiment of an addition reaction that utilizes a platinum (Pt) catalyst. As a prophetic example, a hydride-functionalized siloxane may be blended with the first bio-derived crosslinking material having multiple vinyl groups (1-20% w/w) and Pt catalyst, such as Speier's catalyst (H₂PtCl₆) or Karstedt's catalyst (C₂₄H₅₄O3Pt₂Si₆), and are then mixed. An addition cure reaction via hydrosilation may be performed on the mixture.

FIG. 1A depicts an example in which all three vinyl groups of the bio-derived crosslinking material react in the addition reaction. Depending on the reaction conditions, all three vinyl groups may be used to crosslink the PDMS polymer or less than three vinyl groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the vinyl groups can be used for PDMS crosslinking. The ability to control the number of vinyl groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 1A illustrates an example of a process of forming a bio-derived crosslinking material having multiple vinyl groups from the biorenewable cis-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via an addition reaction. The bio-derived crosslinking material of FIG. 1A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 1B, a chemical reaction diagram 110 illustrates a particular embodiment of a process of utilizing the biorenewable trans-aconitic acid isomer to form a second bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(2)” in FIG. 1B) that includes multiple vinyl groups. FIG. 1B further illustrates that the second bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 1B illustrates that the trans-aconitic acid molecule may be reacted with allyl bromide via a substitution reaction to form a crosslinker with multiple vinyl groups. In some cases, the allyl bromide may be synthesized in one step from biorenewable allyl alcohol. The bio-derived crosslinking material depicted in FIG. 1B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 1A.

The second chemical reaction depicted at the bottom of FIG. 1B illustrates that the bio-derived crosslinking material having multiple vinyl groups may be utilized to form a crosslinked polymeric material (identified as “Crosslinked PDMS Material(2)” in FIG. 1B). The crosslinked polymeric material depicted in FIG. 1B may be formed according to a process that is similar to the process previously described herein with respect to the crosslinked polymeric material of FIG. 1A.

FIG. 1B depicts an example in which all three vinyl groups of the bio-derived crosslinking material react in the addition reaction. Depending on the reaction conditions, all three vinyl groups may be used to crosslink the PDMS polymer or less than three vinyl groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the vinyl groups can be used for PDMS crosslinking. The ability to control the number of vinyl groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 1B illustrates an example of a process of forming a bio-derived crosslinking material having multiple vinyl groups from the biorenewable trans-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via an addition reaction. The bio-derived crosslinking material of FIG. 1B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 2A, a chemical reaction diagram 200 illustrates a particular embodiment of a process of utilizing the biorenewable cis-aconitic acid isomer to form a third bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(3)” in FIG. 2A) that includes multiple acetate groups. FIG. 2A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 2A illustrates that the cis-aconitic acid molecule may be reacted with acetic acid or acetic anhydride via an acylation reaction to form a crosslinker that includes multiple acetate groups. Alternatively, acetyl chloride may be formed from the acetic acid or purchased from a commercial source, and may be used in place of acetic acid along with an amine which may be pyridine or triethylamine. The acetic acid may be obtained from renewable sources, and acetic anhydride can be synthesized from acetic acid.

As a prophetic example, cis-aconitic acid (1 equiv.), acetic acid (4.5-5.0 equiv.), catalytic p-toluenesulfonic acid (or other catalysts such as sulfonic acids, sulfuric acid, phosphoric acid, hydrogen sulfates, dihydrogen phosphates, phosphonic acid esters, or dialkyl tin dioxides) or a Lewis base such as dimethylaminopyridine (DMAP), and a suitable amount of toluene (or other water-azeotrope forming solvents) may be added to a reaction vessel and heated under azeotropic distillation conditions (e.g., refluxing using a Dean-Stark apparatus) until water is no longer removed from the reaction. The mixture may be cooled to room temperature, and the organic layer may be separated, rinsed with water, dried, and purified.

The second chemical reaction depicted at the bottom of FIG. 2A illustrates that the bio-derived crosslinking material having multiple acetate groups may be utilized to form a crosslinked polymeric material via a condensation cure reaction. As a prophetic example, a hydroxy-functionalized siloxane may be mixed with the second bio-derived crosslinker having multiple acetate groups (1-50% w/w) and blended with exclusion of moisture. The blended mixture may be stored under moisture-free conditions. The blended mixture may be applied to surfaces and materials and allowed to cure under atmospheric conditions.

FIG. 2A depicts an example in which all three acetate groups of the bio-derived crosslinking material react in the condensation cure reaction. Depending on the reaction conditions, all three acetate groups may be used to crosslink the PDMS polymer or less than three acetate groups may be used for crosslinking. The ability to control the number of acetate groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 2A illustrates an example of a process of forming a bio-derived crosslinking material having multiple acetate groups from the biorenewable cis-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a condensation cure reaction. The bio-derived crosslinking material of FIG. 2A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 2B, a chemical reaction diagram 210 illustrates a particular embodiment of a process of utilizing the biorenewable trans-aconitic acid isomer to form a fourth bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(4)” in FIG. 2B) that includes multiple acetate groups. FIG. 2B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 2B illustrates that the trans-aconitic acid molecule may be reacted with acetic acid or acetic anhydride via an acylation reaction to form a crosslinker that includes multiple acetate groups. Alternatively, acetyl chloride may be formed from the acetic acid or purchased from a commercial source, and may be used in place of acetic acid along with an amine which may be pyridine or triethylamine. The acetic acid may be obtained from renewable sources, and acetic anhydride can be synthesized from acetic acid. The bio-derived crosslinking material depicted in FIG. 2B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 2A.

The second chemical reaction depicted at the bottom of FIG. 2B illustrates that the bio-derived crosslinking material having multiple acetate groups may be utilized to form a crosslinked polymeric material via a condensation cure reaction. The crosslinked polymeric material depicted in FIG. 2B may be formed according to a process that is similar to the process previously described herein with respect to the crosslinked polymeric material of FIG. 2A.

FIG. 2B depicts an example in which all three acetate groups of the bio-derived crosslinking material react in the condensation cure reaction. Depending on the reaction conditions, all three acetate groups may be used to crosslink the PDMS polymer or less than three acetate groups may be used for crosslinking. The ability to control the number of acetate groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 2B illustrates an example of a process of forming a bio-derived crosslinking material having multiple acetate groups from the biorenewable trans-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a condensation cure reaction. The bio-derived crosslinking material of FIG. 2B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 3A, a chemical reaction diagram 300 illustrates a particular embodiment of a process of utilizing the biorenewable cis-aconitic acid isomer to form a fifth bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(5)” in FIG. 3A) that includes multiple thiol (or mercapto) groups. FIG. 3A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 3A illustrates that the cis-aconitic acid molecule may be reacted with ethyl mercaptoacetic acid via a condensation reaction (acid/base promoted) to synthesize a crosslinker with multiple thiol (or mercapato) groups. The ethyl mercaptoacetic acid may be synthesized from biorenewable acrylic acid via subsequent halogenation and substitution reactions.

As a prophetic example, cis-aconitic acid (1 equiv.), 3-mercaptopropionic acid (4.5-5.0 equiv.), catalytic p-toluenesulfonic acid (or other catalysts such as sulfonic acids, triflic acid, sulfuric acid, phosphoric acid, hydrogen sulfates, dihydrogen phosphates, phosphonic acid esters, or dialkyl tin dioxides) or a Lewis base such as dimethylaminopyridine (DMAP), 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU), or triphenylphosphine, and a suitable amount of toluene (or other water-azeotrope forming solvents) may be added to a reaction vessel and heated under azeotropic distillation conditions (e.g., refluxing using a Dean-Stark apparatus) until water is no longer removed from the reaction. The mixture may be cooled to room temperature, and the organic layer may be separated, rinsed with water, dried, and purified.

The second chemical reaction depicted at the bottom of FIG. 3A illustrates that the bio-derived crosslinking material having multiple thiol groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. As a prophetic example, the bio-derived crosslinking material having multiple thiol groups (2-6% w/w) may be mixed with a vinyl-functionalized siloxane. The mixture may include a radical initiator, such as Micheler's ketone, an alpha-amino-ketone, an alpha-hydroxy-ketone, a benzyldimethyl ketal, or benzophenone (among other alternatives). The mixture may be applied to molds or coated onto a substrate and cured under UV light at a time and temperature suitable to the included radical initiators that are appropriate for the desired applications.

FIG. 3A depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 3A illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the biorenewable cis-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 3A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 3B, a chemical reaction diagram 310 illustrates a particular embodiment of a process of utilizing the biorenewable trans-aconitic acid isomer to form a sixth bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(6)” in FIG. 3B) that includes multiple thiol (or mercapto) groups. FIG. 3B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 3B illustrates that the trans-aconitic acid molecule may be reacted with ethyl mercaptoacetic acid via a condensation reaction (acid/base promoted) to synthesize a crosslinker with multiple thiol (or mercapato) groups. The ethyl mercaptoacetic acid may be synthesized from biorenewable acrylic acid via subsequent halogenation and substitution reactions. The bio-derived crosslinking material depicted in FIG. 3B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 3A.

The second chemical reaction depicted at the bottom of FIG. 3B illustrates that the bio-derived crosslinking material having multiple thiol groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. The crosslinked polymeric material depicted in FIG. 3B may be formed according to a process that is similar to the process previously described herein with respect to the crosslinked polymeric material of FIG. 3A.

FIG. 3B depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 3B illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the biorenewable trans-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 3B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 4A, a chemical reaction diagram 400 illustrates a particular embodiment of a process of utilizing the biorenewable cis-aconitic acid isomer to form a seventh bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(7)” in FIG. 4A) that includes multiple thiol (or mercapto) groups. FIG. 4A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 4A illustrates that the cis-aconitic acid molecule may be utilized to form a crosslinker with multiple thiol (or mercapto) groups via a multiple step reaction that includes the use of an acetate protected thiol bromopropane (commercially available) and substitution chemistry, then removing the protecting group. As a prophetic example, cis-aconitic acid may be added to a suspension or solution of a base (e.g., sodium hydride) in an organic solvent, such as tetrahydrofuran (THF), diethyl ether, or N,N-dimethylformamide (DMF) at 0° C. The reaction mixture may be stirred for 30 minutes before adding S-(3-bromopropyl)ethanethioic acid ester (>3 equiv.), dropwise. The reaction mixture may be stirred for approximately 3 hours, and then neutralized by hydrochloric (HCl) acid. The aqueous and organic layers may then be separated. The aqueous layer may be extracted with diethyl ether, and rinsed with brine. The organic layer may be dried over magnesium sulfate (MgSO₄), and the solvent may be removed in vacuo. The residue may be purified by distillation or column chromatography. The resultant product may be dissolved in DCM at 0° C. and an acid such as trifluoroacetic acid may be added, dropwise. The reaction may be stirred for 3 hours at room temperature, and poured into water. The aqueous and organic layers may then be separated. The aqueous layer may then be extracted with diethyl ether, and rinsed with brine. The organic layer may be dried over magnesium sulfate (MgSO₄), and the solvent may be removed in vacuo. The residue is purified by distillation or column chromatography.

The second chemical reaction depicted at the bottom of FIG. 4A illustrates that the bio-derived crosslinking material having multiple thiol groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. As a prophetic example, the bio-derived crosslinking material having multiple thiol groups (2-6% w/w) may be mixed with a vinyl-functionalized siloxane. The mixture may include a radical initiator, such as Micheler's ketone, an alpha-amino-ketone, an alpha-hydroxy-ketone, a benzyldimethyl ketal, or benzophenone (among other alternatives). The mixture may be applied to molds or coated onto a substrate and cured under UV light at a time and temperature suitable to the included radical initiators that are appropriate for the desired applications.

FIG. 4A depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 4A illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the biorenewable cis-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 4A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 4B, a chemical reaction diagram 410 illustrates a particular embodiment of a process of utilizing the biorenewable trans-aconitic acid isomer to form an eighth bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(8)” in FIG. 4B) that includes multiple thiol (or mercapto) groups. FIG. 4B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 4B illustrates that the trans-aconitic acid molecule may be utilized to form a crosslinker with multiple thiol (or mercapto) groups via a multiple step reaction that includes the use of an acetate protected thiol bromopropane (commercially available) and substitution chemistry, then removing the protecting group. The bio-derived crosslinking material depicted in FIG. 4B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 4A.

The second chemical reaction depicted at the bottom of FIG. 4B illustrates that the bio-derived crosslinking material having multiple thiol groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. The crosslinked polymeric material depicted in FIG. 4B may be formed according to a process that is similar to the process previously described herein with respect to the crosslinked polymeric material of FIG. 4A.

FIG. 4B depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 4B illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the biorenewable trans-aconitic acid isomer and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 4B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

FIGS. 5A and 5B illustrate that the biorenewable molecule aconitic acid may be reduced to a tri-alcohol and used on its own as a cross-linker, with FIG. 5A illustrating the reduction of the cis-aconitic acid isomer and FIG. 5B illustrating the reduction of the trans-aconitic acid isomer. Alternatively, FIGS. 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10A, and 10B illustrate that the reduced aconitic acid molecules of FIGS. 5A and 5B could be further modified with one of a variety of different functional groups that are used to cross-link or cure polymers, like PDMS.

Referring to FIG. 5A, a chemical reaction diagram 500 illustrates a particular embodiment of a process of reducing the biorenewable cis-aconitic acid isomer to a tri-alcohol. The reduced aconitic acid molecule represents a ninth example of a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(9)” in FIG. 5A) that includes multiple hydroxyl groups. FIG. 5A further illustrates that the reduced aconitic acid molecule may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 5A illustrates that the cis-aconitic acid molecule may be reduced to a tri-alcohol, (E)-3-(hydroxymethyl)pent-2-ene-1,5-diol, by lithium aluminum hydride (LiAlH₄). As a prophetic example, for every mole of carboxylic acid, use 3-5 molar equivalents of LiAlH₄. Under inert atmosphere/dry conditions, the carboxylic acid solution may be added dropwise to a solution that includes LiAlH₄ suspended in a solvent, such as tetrahydrofuran (THF) at 0° C. An example workup may include, for every X grams of LiAlH₄, slowly adding X mL of water, X mL of 15-25 percent NaOH (aq) solution, 3X mL of water, then allowing to warm to room temperature and stirring for variable amounts of time. Separated, precipitated salts may be washed, and the combined organic layer and extractions are dried with magnesium sulfate, then filtered.

The second chemical reaction depicted at the bottom of FIG. 5A illustrates that the reduced aconitic acid molecule that includes three hydroxyl functional groups may be utilized to form a crosslinked polymeric material via a condensation cure reaction. FIG. 5 illustrates a particular embodiment of a condensation cure reaction that utilizes dibutyltin dilaurate (DBTDL) as a catalyst. FIG. 5A depicts an example in which all three hydroxyl groups of the reduced aconitic acid molecule react in the condensation cure reaction. Depending on the reaction conditions, all three hydroxyl groups may be used to crosslink the PDMS polymer or less than three hydroxyl groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the hydroxyl groups (e.g., less than three hydroxyl groups per reduced aconitic acid molecule, on average) can be used for PDMS crosslinking. The ability to control the number of hydroxyl groups that react may enable better control of the mechanical properties of the final polymer.

As a prophetic example, a hydride-functionalized siloxane may be blended with the tri-alcohol formed via reduction of the cis-aconitic acid isomer (about 1-20% w/w) and catalyst (DBDTL in this case, 0.1%-2.0% w/w) and mixed. The mixture may be applied to molds or coated onto a substrate and cured for times and temperatures that are appropriate for the desired applications.

Thus, FIG. 5A illustrates an example of a process of reducing the biorenewable cis-aconitic acid isomer to a tri-alcohol, and utilizing the reduced aconitic acid molecule as a bio-derived crosslinking material to form a crosslinked polymeric material via a condensation cure reaction. The bio-derived crosslinking material of FIG. 5A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 5B, a chemical reaction diagram 510 illustrates a particular embodiment of a process of reducing the biorenewable trans-aconitic acid isomer to a tri-alcohol. The reduced aconitic acid molecule represents a tenth example of a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(10)” in FIG. 5B) that includes multiple hydroxyl groups. FIG. 5B further illustrates that the reduced aconitic acid molecule may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 5B illustrates that the trans-aconitic acid molecule may be reduced to a tri-alcohol, (Z)-3-(hydroxymethyl)pent-2-ene-1,5-diol, by lithium aluminum hydride. The tri-alcohol depicted in FIG. 5B may be formed from the trans-aconitic acid isomer according to a process that is similar to the process previously described herein with respect to the tri-alcohol of FIG. 5A.

The second chemical reaction depicted at the bottom of FIG. 5B illustrates that the reduced aconitic acid molecule that includes three hydroxyl functional groups may be utilized to form a crosslinked polymeric material via a condensation cure reaction. The crosslinked polymeric material depicted in FIG. 5B may be formed according to a process that is similar to the process previously described herein with respect to the crosslinked polymeric material of FIG. 5A.

FIG. 5B depicts an example in which all three hydroxyl groups of the reduced aconitic acid molecule react in the condensation cure reaction. Depending on the reaction conditions, all three hydroxyl groups may be used to crosslink the PDMS polymer or less than three hydroxyl groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the hydroxyl groups (e.g., less than three hydroxyl groups per reduced aconitic acid molecule, on average) can be used for PDMS crosslinking. The ability to control the number of hydroxyl groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 5B illustrates an example of a process of reducing the biorenewable trans-aconitic acid isomer to a tri-alcohol, and utilizing the reduced aconitic acid molecule as a bio-derived crosslinking material to form a crosslinked polymeric material via a condensation cure reaction. The bio-derived crosslinking material of FIG. 5B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

FIGS. 6A, 7A, 8A, 9A, and 10A illustrate examples of bio-derived crosslinking materials that may be formed from the reduced cis-aconitic acid molecule that may be synthesized according to the process previously described herein with respect to FIG. 5A. FIGS. 6A, 7A, 8A, 9A, and 10A illustrate that the reduced cis-aconitic acid molecule may be further modified with one of a variety of different functional groups that are used to cross-link or cure polymers, like PDMS. FIGS. 6B, 7B, 8B, 9B, and 10B illustrate examples of bio-derived crosslinking materials that may be formed from the reduced trans-aconitic acid molecule that may be synthesized according to the process previously described herein with respect to FIG. 5B. FIGS. 6B, 7B, 8B, 9B, and 10B illustrate that the reduced trans-aconitic acid molecule may be further modified with one of a variety of different functional groups that are used to cross-link or cure polymers, like PDMS.

Referring to FIG. 6A, a chemical reaction diagram 600 illustrates a particular embodiment of a process of utilizing the reduced cis-aconitic acid molecule of FIG. 5A to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(11)” in FIG. 6A) that includes multiple acrylate groups. FIG. 6A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 6A illustrates that the reduced cis-aconitic acid molecule of FIG. 5A may be reacted with acrylic acid via acid- (or base-) catalyzed condensation reaction to form a crosslinker with multiple acrylate groups. Alternatively, acryloyl chloride may be formed from the acrylic acid, and may be used in place of acrylic acid along with an amine which may be pyridine or triethylamine. The acrylic acid may be formed from biorenewable resource(s).

As a prophetic example, the reduced cis-aconitic acid molecule (1 equiv.), acrylic acid (4.5-5.0 equiv.), catalytic p-toluenesulfonic acid (or other catalysts such as sulfonic acids, sulfuric acid, phosphoric acid, hydrogen sulfates, dihydrogen phosphates, phosphonic acid esters, or dialkyl tin dioxides) or a Lewis base such as dimethylaminopyridine (DMAP), and a suitable amount of toluene (or other water-azeotrope forming solvents) may be added to a reaction vessel and heated under azeotropic distillation conditions (e.g., refluxing using a Dean-Stark apparatus) until water is no longer removed from the reaction. The mixture may be cooled to room temperature, and the organic layer may be separated, rinsed with water, dried, and purified.

The second chemical reaction depicted at the bottom of FIG. 6A illustrates that the bio-derived crosslinking material having multiple acrylate groups may be utilized to form a crosslinked polymeric material. FIG. 6A illustrates a particular embodiment of an addition reaction that utilizes a platinum (Pt) catalyst. As a prophetic example, a hydride-functionalized siloxane may be blended with the bio-derived crosslinking material having multiple acrylate groups (1-20% w/w) and Pt catalyst, such as Speier's catalyst (H₂PtCl₆) or Karstedt's catalyst (C₂₄H₅₄O₃Pt₂Si₆), and are then mixed. An addition cure reaction via hydrosilation may be performed on the mixture.

FIG. 6A depicts an example in which all three acrylate groups of the bio-derived crosslinking material react in the addition reaction. Depending on the reaction conditions, all three acrylate groups may be used to crosslink the PDMS polymer or less than three acrylate groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the acrylate groups can be used for PDMS crosslinking. The ability to control the number of acrylate groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 6A illustrates an example of a process of forming a bio-derived crosslinking material having multiple acrylate groups from the reduced cis-aconitic acid molecule of FIG. 5A and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via an addition reaction. The bio-derived crosslinking material of FIG. 6A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 6B, a chemical reaction diagram 610 illustrates a particular embodiment of a process of utilizing the reduced trans-aconitic acid molecule of FIG. 5B to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(12)” in FIG. 6B) that includes multiple acrylate groups. FIG. 6B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 6B illustrates that the reduced trans-aconitic acid molecule of FIG. 5B may be reacted with acrylic acid via an acid- (or base-) catalyzed condensation reaction to form a crosslinker with multiple acrylate groups. Alternatively, acryloyl chloride may be formed from the acrylic acid, and may be used in place of acrylic acid along with an amine which may be pyridine or triethylamine. The acrylic acid may be formed from biorenewable resource(s). The bio-derived crosslinking material depicted in FIG. 6B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 6A.

The second chemical reaction depicted at the bottom of FIG. 6B illustrates that the bio-derived crosslinking material having multiple acrylate groups may be utilized to form a crosslinked polymeric material. FIG. 6B illustrates a particular embodiment of an addition reaction that utilizes a platinum (Pt) catalyst. The crosslinked polymeric material depicted in FIG. 6B may be formed according to a process that is similar to the process previously described herein with respect to the crosslinked polymeric material of FIG. 6A.

FIG. 6B depicts an example in which all three acrylate groups of the bio-derived crosslinking material react in the addition reaction. Depending on the reaction conditions, all three acrylate groups may be used to crosslink the PDMS polymer or less than three acrylate groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the acrylate groups can be used for PDMS crosslinking. The ability to control the number of acrylate groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 6B illustrates an example of a process of forming a bio-derived crosslinking material having multiple acrylate groups from the reduced trans-aconitic acid molecule of FIG. 5B and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via an addition reaction. The bio-derived crosslinking material of FIG. 6B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 7A, a chemical reaction diagram 700 illustrates a particular embodiment of a process of utilizing the reduced cis-aconitic acid molecule of FIG. 5A to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(13)” in FIG. 7A) that includes multiple vinyl groups. FIG. 7A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 7A illustrates that the reduced cis-aconitic acid molecule of FIG. 5A may be reacted with allyl bromide via a substitution reaction to form a crosslinker with multiple vinyl groups. In some cases, the allyl bromide may be synthesized in one step from biorenewable allyl alcohol. The bio-derived crosslinking material depicted in FIG. 7A may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 1A.

The second chemical reaction depicted at the bottom of FIG. 7A illustrates that the bio-derived crosslinking material having multiple vinyl groups may be utilized to form a crosslinked polymeric material via an addition reaction. The cross-linking reaction depicted in FIG. 7A may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 1A.

FIG. 7A depicts an example in which all three vinyl groups of the bio-derived crosslinking material react in the addition reaction. Depending on the reaction conditions, all three vinyl groups may be used to crosslink the PDMS polymer or less than three vinyl groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the vinyl groups can be used for PDMS crosslinking. The ability to control the number of vinyl groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 7A illustrates an example of a process of forming a bio-derived crosslinking material having multiple vinyl groups from the reduced cis-aconitic acid molecule of FIG. 5A and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via an addition reaction. The bio-derived crosslinking material of FIG. 7A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 7B, a chemical reaction diagram 710 illustrates a particular embodiment of a process of utilizing the reduced trans-aconitic acid molecule of FIG. 5B to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(14)” in FIG. 7B) that includes multiple vinyl groups. FIG. 7B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 7B illustrates that the reduced trans-aconitic acid molecule of FIG. 5B may be reacted with allyl bromide via a substitution reaction to form a crosslinker with multiple vinyl groups. In some cases, the allyl bromide may be synthesized in one step from biorenewable allyl alcohol. The bio-derived crosslinking material depicted in FIG. 7B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 1B.

The second chemical reaction depicted at the bottom of FIG. 7B illustrates that the bio-derived crosslinking material having multiple vinyl groups may be utilized to form a crosslinked polymeric material via an addition reaction. The cross-linking reaction depicted in FIG. 7B may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 1B.

FIG. 7B depicts an example in which all three vinyl groups of the bio-derived crosslinking material react in the addition reaction. Depending on the reaction conditions, all three vinyl groups may be used to crosslink the PDMS polymer or less than three vinyl groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the vinyl groups can be used for PDMS crosslinking. The ability to control the number of vinyl groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 7B illustrates an example of a process of forming a bio-derived crosslinking material having multiple vinyl groups from the reduced trans-aconitic acid molecule of FIG. 5B and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via an addition reaction. The bio-derived crosslinking material of FIG. 7B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 8A, a chemical reaction diagram 800 illustrates a particular embodiment of a process of utilizing the reduced cis-aconitic acid molecule of FIG. 5A to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(15)” in FIG. 8A) that includes multiple acetate groups. FIG. 8A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 8A illustrates that the reduced cis-aconitic acid molecule of FIG. 5A may be reacted with acetic acid or acetic anhydride via an acylation reaction to form a crosslinker that includes multiple acetate groups. The bio-derived crosslinking material depicted in FIG. 8A may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 2A.

The second chemical reaction depicted at the bottom of FIG. 8A illustrates that the bio-derived crosslinking material having multiple acetate groups may be utilized to form a crosslinked polymeric material via a condensation cure reaction. The cross-linking reaction depicted in FIG. 8A may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 2A.

FIG. 8A depicts an example in which all three acetate groups of the bio-derived crosslinking material react in the condensation cure reaction. Depending on the reaction conditions, all three acetate groups may be used to crosslink the PDMS polymer or less than three acetate groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the acetate groups can be used for PDMS crosslinking. The ability to control the number of acetate groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 8A illustrates an example of a process of forming a bio-derived crosslinking material having multiple acetate groups from the reduced cis-aconitic acid molecule of FIG. 5A and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a condensation cure reaction. The bio-derived crosslinking material of FIG. 8A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 8B, a chemical reaction diagram 810 illustrates a particular embodiment of a process of utilizing the reduced trans-aconitic acid molecule of FIG. 5B to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(16)” in FIG. 8B) that includes multiple acetate groups. FIG. 8B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 8B illustrates that the reduced trans-aconitic acid molecule of FIG. 5B may be reacted with acetic acid or acetic anhydride via an acylation reaction to form a crosslinker that includes multiple acetate groups. The bio-derived crosslinking material depicted in FIG. 8B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 2B.

The second chemical reaction depicted at the bottom of FIG. 8B illustrates that the bio-derived crosslinking material having multiple acetate groups may be utilized to form a crosslinked polymeric material via a condensation cure reaction. The cross-linking reaction depicted in FIG. 8B may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 2B.

FIG. 8B depicts an example in which all three acetate groups of the bio-derived crosslinking material react in the condensation cure reaction. Depending on the reaction conditions, all three acetate groups may be used to crosslink the PDMS polymer or less than three acetate groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the acetate groups can be used for PDMS crosslinking. The ability to control the number of acetate groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 8B illustrates an example of a process of forming a bio-derived crosslinking material having multiple acetate groups from the reduced trans-aconitic acid molecule of FIG. 5B and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a condensation cure reaction. The bio-derived crosslinking material of FIG. 8B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 9A, a chemical reaction diagram 900 illustrates a particular embodiment of a process of utilizing the reduced cis-aconitic acid molecule of FIG. 5A to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(17)” in FIG. 9A) that includes multiple thiol (or mercapto) groups. FIG. 9A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 9A illustrates that the reduced cis-aconitic acid molecule of FIG. 5A may be reacted with ethyl mercaptoacetic acid via a condensation reaction (acid/base promoted) to form a bio-derived crosslinking material with multiple thiol (or mercapato) groups. The bio-derived crosslinking material depicted in FIG. 9A may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 3A.

The second chemical reaction depicted at the bottom of FIG. 9A illustrates that the bio-derived crosslinking material with multiple thiol (or mercapato) groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. The cross-linking reaction depicted in FIG. 9A may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 3A.

FIG. 9A depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the thiol groups can be used for PDMS crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 9A illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the reduced cis-aconitic acid molecule of FIG. 5A and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 9A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 9B, a chemical reaction diagram 910 illustrates a particular embodiment of a process of utilizing the reduced trans-aconitic acid molecule of FIG. 5B to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(18)” in FIG. 9B) that includes multiple thiol (or mercapto) groups. FIG. 9B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 9B illustrates that the reduced trans-aconitic acid molecule of FIG. 5B may be reacted with ethyl mercaptoacetic acid via a condensation reaction (acid/base promoted) to form a bio-derived crosslinking material with multiple thiol (or mercapato) groups. The bio-derived crosslinking material depicted in FIG. 9B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 3B.

The second chemical reaction depicted at the bottom of FIG. 9B illustrates that the bio-derived crosslinking material with multiple thiol (or mercapato) groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. The cross-linking reaction depicted in FIG. 9B may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 3B.

FIG. 9B depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the thiol groups can be used for PDMS crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 9B illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the reduced trans-aconitic acid molecule of FIG. 5B and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 9B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 10A, a chemical reaction diagram 1000 illustrates a particular embodiment of a process of utilizing the reduced cis-aconitic acid molecule of FIG. 5A to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(19)” in FIG. 10A) that includes multiple thiol (or mercapto) groups. FIG. 10A further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 10A illustrates that the reduced cis-aconitic acid molecule of FIG. 5A may be utilized to form a crosslinker with multiple thiol (or mercapto) groups via a multiple step reaction that includes the use of an acetate protected thiol bromopropane (commercially available) and substitution chemistry, then removing the protecting group. The bio-derived crosslinking material depicted in FIG. 9A may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 4A.

The second chemical reaction depicted at the bottom of FIG. 10A illustrates that the bio-derived crosslinking material having multiple thiol groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. The cross-linking reaction depicted in FIG. 10A may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 4A.

FIG. 10A depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the thiol groups can be used for PDMS crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 10A illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the reduced cis-aconitic acid molecule of FIG. 5A and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 10A may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

Referring to FIG. 10B, a chemical reaction diagram 1010 illustrates a particular embodiment of a process of utilizing the reduced trans-aconitic acid molecule of FIG. 5B to form a bio-derived crosslinking material (identified as “Bio-Derived Crosslinker(20)” in FIG. 10B) that includes multiple thiol (or mercapto) groups. FIG. 10B further illustrates that the bio-derived crosslinking material may be utilized to form a crosslinked polymeric material (e.g., a crosslinked PDMS material), according to one embodiment.

The first chemical reaction depicted at the top of FIG. 10B illustrates that the reduced trans-aconitic acid molecule of FIG. 5B may be utilized to form a crosslinker with multiple thiol (or mercapto) groups via a multiple step reaction that includes the use of an acetate protected thiol bromopropane (commercially available) and substitution chemistry, then removing the protecting group. The bio-derived crosslinking material depicted in FIG. 10B may be formed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 4B.

The second chemical reaction depicted at the bottom of FIG. 10B illustrates that the bio-derived crosslinking material having multiple thiol groups may be utilized to form a crosslinked polymeric material via a thiol-ene cure reaction. The cross-linking reaction depicted in FIG. 10B may be performed according to a process that is similar to the process previously described herein with respect to the bio-derived crosslinking material of FIG. 4B.

FIG. 10B depicts an example in which all three thiol groups of the bio-derived crosslinking material react in the thiol-ene cure reaction. Depending on the reaction conditions, all three thiol groups may be used to crosslink the PDMS polymer or less than three thiol groups may be used for crosslinking. To illustrate, by controlling the reaction conditions, catalyst type (other tin or platinum catalyst may be used), catalyst loading, and stoichiometry, a fraction of the thiol groups can be used for PDMS crosslinking. The ability to control the number of thiol groups that react may enable better control of the mechanical properties of the final polymer.

Thus, FIG. 10B illustrates an example of a process of forming a bio-derived crosslinking material having multiple thiol (or mercapto) groups from the reduced trans-aconitic acid molecule of FIG. 5B and utilizing the bio-derived crosslinking material to form a crosslinked polymeric material via a thiol-ene cure reaction. The bio-derived crosslinking material of FIG. 10B may be used to increase the biorenewable content of a resulting crosslinked polymeric material (e.g., a crosslinked PDMS material).

It will be understood from the foregoing description that modifications and changes may be made in various embodiments of the present invention without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense. The scope of the present invention is limited only by the language of the following claims. 

What is claimed is:
 1. A process of forming a crosslinked polymeric material, the process comprising: forming a bio-derived crosslinking material from a biorenewable aconitic acid molecule, the bio-derived crosslinking material including multiple vinyl groups or acrylate groups; and chemically reacting the bio-derived crosslinking material with a hydride-functionalized polydimethylsiloxane (PDMS) polymer to form a crosslinked PDMS material.
 2. The process of claim 1, wherein chemically reacting the bio-derived crosslinking material with the hydride-functionalized PDMS polymer includes an addition reaction.
 3. The process of claim 1, wherein the biorenewable aconitic acid molecule includes a cis-aconitic acid isomer, a trans-aconitic acid isomer, or a combination thereof.
 4. The process of claim 1, wherein forming the bio-derived crosslinking material includes chemically reacting the biorenewable aconitic acid molecule with allyl bromide to convert carboxylic acid groups of the biorenewable aconitic acid molecule to vinyl groups.
 5. The process of claim 1, wherein forming the bio-derived crosslinking material includes: converting carboxylic acid groups of the biorenewable aconitic acid molecule to hydroxyl groups; and converting the hydroxyl groups to the vinyl groups or the acrylate groups to form the bio-derived crosslinking material.
 6. The process of claim 1, wherein a subset of the multiple vinyl groups or acrylate groups chemically react with the hydride-functionalized PDMS polymer.
 7. A process of forming a crosslinked polymeric material, the process comprising: forming a bio-derived crosslinking material from a biorenewable aconitic acid molecule, the bio-derived crosslinking material including multiple acetate groups; and chemically reacting the bio-derived crosslinking material with a hydroxyl-functionalized polydimethylsiloxane (PDMS) polymer to form a crosslinked PDMS material.
 8. The process of claim 7, wherein chemically reacting the bio-derived crosslinking material with the hydroxy-functionalized PDMS polymer includes a condensation cure reaction.
 9. The process of claim 7, wherein forming the bio-derived crosslinking material includes chemically reacting the biorenewable aconitic acid molecule with acetic acid or acetic anhydride to convert carboxylic acid groups of the biorenewable aconitic acid molecule to acetate groups.
 10. The process of claim 7, wherein forming the bio-derived crosslinking material includes: converting carboxylic acid groups of the biorenewable aconitic acid molecule to hydroxyl groups; and utilizing acetic acid or acetic anhydride to convert the hydroxyl groups to acetate groups to form the bio-derived crosslinking material that includes multiple acetate groups.
 11. The process of claim 7, wherein the biorenewable aconitic acid molecule includes a cis-aconitic acid isomer, a trans-aconitic acid isomer, or a combination thereof.
 12. The process of claim 7, wherein a subset of the multiple acetate groups chemically react with the hydroxy-functionalized PDMS polymer.
 13. A process of forming a crosslinked polymeric material, the process comprising: forming a bio-derived crosslinking material from a biorenewable aconitic acid molecule, the bio-derived crosslinking material including multiple thiol groups; and chemically reacting the bio-derived crosslinking material with a vinyl-functionalized polydimethylsiloxane (PDMS) polymer to form a crosslinked PDMS material.
 14. The process of claim 13, wherein chemically reacting the bio-derived crosslinking material with the vinyl-functionalized PDMS polymer includes a thiol-ene cure reaction.
 15. The process of claim 13, wherein forming the bio-derived crosslinking material includes chemically reacting the biorenewable aconitic acid molecule with ethyl mercaptoacetic acid to convert carboxylic acid groups of the biorenewable aconitic acid molecule to thiol groups.
 16. The process of claim 13, wherein forming the bio-derived crosslinking material includes a multiple step reaction that includes utilizing an acetate protected thiol bromopropane and substitution chemistry followed by removal of protecting groups.
 17. The process of claim 13, wherein forming the bio-derived crosslinking material includes: converting carboxylic acid groups of the biorenewable aconitic acid molecule to hydroxyl groups; and converting the hydroxyl groups to thiol groups to form the bio-derived crosslinking material that includes multiple thiol groups.
 18. The process of claim 17, wherein ethyl mercaptoacetic acid is utilized to convert the hydroxyl groups to thiol groups via a condensation reaction.
 19. The process of claim 13, wherein the biorenewable aconitic acid molecule includes a cis-aconitic acid isomer, a trans-aconitic acid isomer, or a combination thereof.
 20. The process of claim 13, wherein a subset of the multiple thiol groups chemically react with the vinyl-functionalized PDMS polymer. 